refactor(ui): consolidate dialog footers + shared empty-state, unify buttons/rounding

Addresses the cross-screen inconsistencies from the layout audit by routing screens onto
the design system's own (previously under-used) shared helpers:

- Dialog footers: migrate ~9 overlay dialogs off hand-rolled placement onto the shared
  helpers — DialogActionFooter (primary+Close), DialogConfirmFooter, or
  BeginOverlayDialogFooter for custom/multi-button rows — so footers share one centered
  treatment. All footer/action buttons now use TactileButton (glass press) instead of the
  bare StyledButton some dialogs used.
- Empty states: add a shared material::DrawEmptyState(icon, title, hint) (centered icon +
  title + wrapped hint) and adopt it in Peers, Transactions, and Market-portfolio, which
  previously showed a bare left-aligned caption.
- Security dialogs: add the missing Cancel to Change Passphrase and Set PIN so the whole
  security family shares a two-button footer (Cancel dismisses without applying).
- Transactions pager: shared TactileButton helpers (matching Explorer).
- Frosted-pane rounding: Contacts/Chat use Layout::glassRounding() instead of hardcoded
  12/10/8px literals, matching Peers.
- "Set Label..." title loses its stray trailing ellipsis.

Preserves every button's label and action; the transfer footer's order becomes
[Confirm][Cancel] to match the shared helper's primary-first convention. Verified at 1280
across full-node + Lite + Windows (ctest green) and an adversarial diff review (clean).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/ui/windows/validate_address_dialog.cpp

@@ -210,11 +210,10 @@ void ValidateAddressDialog::render(App* app)
             ImGui::TextColored(ImVec4(1.0f, 0.6f, 0.0f, 1.0f), "%s", TR("not_connected"));
         }
 
-        ImGui::Spacing();
-        
-        // Close button at bottom
+        // Close button at bottom — centered via the shared footer helper (no separator, matching
+        // the prior hand-rolled placement).
         float button_width = closeBtn.width;
-        ImGui::SetCursorPosX((ImGui::GetWindowWidth() - button_width) / 2.0f);
+        material::BeginOverlayDialogFooter(button_width, /*drawSeparator=*/false);
         if (material::TactileButton(TR("close"), ImVec2(button_width, 0), S.resolveFont(closeBtn.font))) {
             s_open = false;
         }